Python Add Items to Dictionaries

In Python, dictionaries are versatile data structures that store data in key-value pairs. One of the key features of dictionaries is the ability to add new items dynamically. This lesson will guide you through the process of adding new entries to a dictionary and updating existing ones.

1. Adding Items to a Dictionary

To add an item to a dictionary, you simply specify a new key and assign a value to it. This operation is straightforward and allows you to expand your dictionary's contents as needed.

Example: Adding a New Item

1# Creating a dictionary for a smartphone
2smartphone_specs = {
3    "brand": "Samsung",
4    "model": "Galaxy S21",
5    "year": 2021
6}
7
8# Adding a new item for color
9smartphone_specs["color"] = "Phantom Gray"
10
11print(smartphone_specs)  # Output: {'brand': 'Samsung', 'model': 'Galaxy S21', 'year': 2021, 'color': 'Phantom Gray'}

In this example, the new key "color" is added to the smartphone_specs dictionary, allowing you to store more information about the smartphone.

2. Updating the Dictionary with update()

The update() method is a powerful way to add or modify multiple items in a dictionary at once. This method takes a dictionary or an iterable of key-value pairs as its argument.

Example: Using update() to Add Items

1# Creating a dictionary for a laptop
2laptop_details = {
3    "brand": "Dell",
4    "model": "XPS 13",
5    "year": 2020
6}
7
8# Adding multiple items using update()
9laptop_details.update({"color": "Silver", "RAM": "16GB"})
10
11print(laptop_details)  # Output: {'brand': 'Dell', 'model': 'XPS 13', 'year': 2020, 'color': 'Silver', 'RAM': '16GB'}

In this example, we use update() to add both the "color" and "RAM" entries to the laptop_details dictionary in one step.

3. Adding Items Using an Iterable

You can also use an iterable object, like a list of tuples, to add multiple key-value pairs at once. This can streamline the process when you have several items to add.

Example: Adding Items from a List of Tuples

1# Creating a dictionary for a book
2book_info = {
3    "title": "1984",
4    "author": "George Orwell",
5    "published": 1949
6}
7
8# List of new attributes as tuples
9new_attributes = [("genre", "Dystopian"), ("pages", 328)]
10
11# Adding new attributes using a loop
12for key, value in new_attributes:
13    book_info[key] = value
14
15print(book_info)  # Output: {'title': '1984', 'author': 'George Orwell', 'published': 1949, 'genre': 'Dystopian', 'pages': 328}

In this example, we iterate through a list of tuples, adding each new attribute to the book_info dictionary.